Yao Zan, Chen Yuhang
Opt Express. 2021 Feb 1;29(3):3904-3914. doi: 10.1364/OE.412403.
Metalenses are a kind of flat optical device, which consist of an array of nanoantennas with subwavelength thickness that manipulates the incoming light wavefront in a precisely tailorable manner. In this work, we proposed a bifocal metalens that can realize switchable multiplane imaging, controlled by changing the polarization state of an incident light. The polarization-dependent metalens was designed and fabricated by arranging polysilicon nanobeam unit elements. We simulated and experimentally characterized the focus performance of the bifocal metalens. Under the light incidence with left-handed circular polarization, the focal length is 250 µm. By changing the polarization state to right-handed circular polarization, the focal length is tuned to 200 µm. Experimental results and numerical simulations are in good agreement. Moreover, when a linear polarization light is used, two focal spots will appear at the same time. Such a bifocal metalens is suitable for multiplane imaging applications.
超构透镜是一种平面光学器件，它由一系列具有亚波长厚度的纳米天线阵列组成，能够以精确可定制的方式操纵入射光波前。在这项工作中，我们提出了一种双焦点超构透镜，它可以通过改变入射光的偏振态来实现可切换的多平面成像。通过排列多晶硅纳米梁单元元件来设计和制造偏振依赖型超构透镜。我们对双焦点超构透镜的聚焦性能进行了模拟和实验表征。在左旋圆偏振光入射下，焦距为250μm。通过将偏振态改变为右旋圆偏振光，焦距调谐到200μm。实验结果与数值模拟结果吻合良好。此外，当使用线偏振光时，会同时出现两个焦点。这种双焦点超构透镜适用于多平面成像应用。
